Cosmology with Higher Order Statistics of Galaxy Clustering

Speaker: Naonori Sugiyama (NAOJ)


Currently, cosmology with galaxy clustering is entering a golden age in Japan. The Prime Focus Spectrograph (PFS) project will start in 2023 and will provide the world’s highest quality data on galaxy redshifts. The resulting three-dimensional map of the Universe enables to tackle some of the most fundamental questions in astrophysics, such as proving the effects of dark energy on the expansion history, testing modified gravity theories, limiting the sum of neutrino masses, and studying the signatures of primordial inflation. In this context, what can I contribute to the PFS project?
 My research goal is to extract full cosmological information from observed galaxy data. To do this, I focus on three-point statistics of galaxy clustering. Usually, the two-point statistics have been used in the analysis of galaxy data, but it is known that non-linear gravitational effects can leak information into higher-order statistics. Thus, it is essential to include higher-order statistics beyond the two-point statistics. However,  there have been still a debate about how to analyze the three-point statistics. For the first time, I have established a method for the analysis of the three-point statistics and applied it to the current galaxy data obtained from the BOSS project. The results show that the use of the three-point statistics improves the cosmological parameter constraints by a factor of ~ 1.4.